1. Technical Field of the Invention
The present invention relates to a device for shaping a corrugated fin into a wave shape with its bent portions successively connected and, more particularly, to shaping a bent portion.
2. Description of the Related Art
In a conventional device for shaping a corrugated fin of this type, for example, the one described in Japanese Unexamined Patent Publication (Kokai) No. H08-261678, by feeding a fin material between a pair of gear-like forming rollers from a material roll around which a thin plate-like fin material is wound, a number of bent portions are formed and a corrugated fin is formed into a wave shape and, at the same time, a heat exchange section for promoting heat exchange is formed on a surface continuous with the bent portion and thus a wave-shaped corrugated fin is formed.
Further, a forming device is known which continuously performs shaping in order to obtain a predetermined shape and a predetermined fin pitch by performing a compression process for compressing a wave-shaped corrugated fin formed by being passed through a forming roller in its lengthwise direction and a stretch process for stretching the compressed fin material by a predetermined distance in its lengthwise direction while holding both ends.
However, in the compression process for performing shaping as described in Japanese Unexamined Patent Publication (Kokai) No. H08-261678, the known forming device is made so as to include a feeding roller for feeding forward a wave-shaped corrugated fin and a friction application section for applying a frictional resistance to the corrugated fin to be fed, and the corrugated fin is compressed in its lengthwise direction by compressing it so that a number of bent portions come into contact with each another at one time.
Because of this, it is not possible to apply a uniform compression force to each ridge and, therefore, there may be a case where the amount of displacement of a portion to which a strong compression force is applied or of a portion vulnerable to bending force becomes large and in particular, a collapse begins from a bent portion with a small strength, resulting in that the shape of the bent portion is not formed into a predetermined shape.
In particular, if a bent portion is required to have, for example, a portal shape, it is difficult to obtain a predetermined shape that meets a required precision regarding the irregularity or inclination of the planar portion. Further, it is recommended to provide a shaping device capable of shaping a planar portion by providing a shaping mechanism inside and outside a bent portion for each ridge after compression formation in order to shape the planar portion into a stable shape, however, there arises a problem in that a complex shaping device is required and the facility cost for the device is increased.